The present invention relates to novel pyrido[4,3-d]pyrimidine derivatives, pharmaceutically acceptable salts thereof and pharmaceutical compositions containing them as an active ingredient.
It is known that the so-called "chemical mediator", i.e. histamine, serotonin or SRS-A, plays an important role in the appearance of various allergic symptoms in the human body. A pharmaceutical which antagonizes such biochemical substances and/or inhibits their release would be useful for treating or preventing allergic diseases. There have been several prior attempts to synthesize such compounds.
It has been found that certain pyrido[4,3-d]pyrimidine derivatives have an excellent anti-allergic effect.
An object of the present invention is to provide novel pyrido[4,3-d]pyrimidine derivatives and pharmaceutically acceptable salts thereof useful for treating or mitigating the effects of allergic diseases as well as possessing low toxicity and fewer side effects. Another object of the invention is to provide pharmaceutical compositions containing at least one of the pyrido[4,3-d]pyrimidine derivatives or pharmaceutically acceptable salts thereof as an active ingredient. A further object of the present invention is to provide a method for treating mammals suffering from bronchial asthma, urticaria, allergic rhinitis, allergic dermatoses or allergic conjunctivitis which comprises administering thereto the compounds of the invention.